X-Ray Scattering from Soft-Matter Thin Films

Tolan, Metin

doi:10.1007/bfb0112834

Cited by 478 publications

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“…In standard procedure (see, for example Ref. [18]) the interfacial structure is divided into N layers. Each layer has a thickness l j and electron density j ρ .…”

Section: Electron-density Profilementioning

confidence: 99%

X-ray study of the electric double layer at the n-hexane/nanocolloidal silica interface

Tikhonov

2006

The Journal of Chemical Physics

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The spatial structure of the transition region between an insulator and an electrolyte solution was studied with x-ray scattering. The electron-density profile across the n-hexane/silica sol interface (solutions with 5, 7, and 12 nm colloidal particles) agrees with the theory of the electrical double layer and shows separation of positive and negative charges. The interface consists of three layers, i.e., a compact layer of Na(+), a loose monolayer of nanocolloidal particles as part of a thick diffuse layer, and a low-density layer sandwiched between them. Its structure is described by a model in which the potential gradient at the interface reflects the difference in the potentials of "image forces" between the cationic Na(+) and anionic nanoparticles and the specific adsorption of surface charge. The density of water in the large electric field (approximately 10(9)-10(10) Vm) of the transition region and the layering of silica in the diffuse layer is discussed.

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“…In standard procedure (see, for example Ref. [18]) the interfacial structure is divided into N layers. Each layer has a thickness l j and electron density j ρ .…”

Section: Electron-density Profilementioning

confidence: 99%

X-ray study of the electric double layer at the n-hexane/nanocolloidal silica interface

Tikhonov

2006

The Journal of Chemical Physics

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“…The oscillation period ΔP appears to decrease with increasing concentration of the aqueous solution. As the thickness d is proportional to the reciprocal of ΔP [21], this result implies that …”

Section: Estimation Of Film Thickness Of Spun-filmsmentioning

confidence: 94%

“…Specular X-ray reflectivity (XRR) is a unique and powerful analytical method (Figure 2) that is frequently applied to condensed soft-matter films, including glass transition studies of ultrathin polymer films [16][17][18][19][20], but which has not been applied in amorphous sugar studies. XRR can evaluate the layered structure of a material, such as the film thickness, electron density, surface roughness, and interfacial width [21,22]. When the incident X-ray angle in the 2θ/ω scan exceeds the total reflection critical angle (θ C ), some of the X-rays penetrate the first layer, while the others reflect from the first-layer surface (Figure 2a).…”

Section: Introductionmentioning

confidence: 99%

“…Oscillation fringes are called "Kiessig fringes" after Kiessig, who first reported them in 1931 [23]. The oscillation period ΔP [radian] heavily depends on the film thickness, d; specifically, d is approximated by λ/ (2ΔP), where λ is the X-ray wavelength [21], and is often calculated by fitting the X-ray profiles using an appropriate software [22]. In conventional X-ray optics with multilayer mirrors, this method is highly sensitive to the vertical length scale, which varies from 0.5 to 100 nm.…”

Section: Introductionmentioning

confidence: 99%

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Glass Transition of Ultrathin Sugar Films Probed by X-Ray Reflectivity

Ogawa¹,

Takahashi²

2017

Carbohydrate

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Besides being the main types of carbohydrate in food, sugars are a representative protectant in biopharmaceutical formulations. To identify the protection mechanism, researchers have extensively investigated the bulk physicochemical properties of sugars. However, whereas the glass transition of sugar has been widely studied and debated, the physicochemical properties of sugar molecules in confined circumstances such as nanometer thick films remain largely unknown. In this chapter, we introduce an experimental procedure for analyzing the glass transition of sugars in ultrathin films. The analysis is based on X-ray reflectivity (XRR) analysis, which has been often applied in glass transition studies of polymer films, but never in sugar media.

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“…X-ray reflectivity is extremely sensitive to the layered structure along the depth of the film on the angstrom to nanometer scale. 23,24 As a result, one can study the thermoresponsive behavior of a PNIPAM solid ultrathin film by measuring the thickness during heating and cooling. This experiment shows that the PNIPAM solid ultrathin film changes thickness from 190 to 203 ¡ in response to heating and cooling, even without any direct contact with bulk water.…”

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confidence: 99%

Thermoresponsive Behavior of Poly(N-isopropylacrylamide) Solid Ultrathin Film under Ordinary Atmospheric Conditions

Liu

Sakurai

2017

Chem. Lett.

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Significant changes in the thickness of poly(N-isopropylacrylamide) solid ultrathin films have been observed by X-ray reflectivity as a result of changing the temperature between 15 and 60°C in an uncontrolled atmosphere. As the property of the film switches between hydrophobic and hydrophilic nature at around 33°C, the present letter reports that an ultrathin film of around 200 ¡ exhibits nearly a 7% change in thickness even in an ordinary atmosphere and that cooling and heating exhibit different dependence; i.e., one can confirm the switching point in the cooling run, but the dependence is linear in the heating run. The phenomena are reproducible and repeatable.Keywords: PNIPAM solid ultrathin film | X-ray reflectivity | ThicknessThermoresponsive polymers have already attracted considerable attention as intelligent materials due to the various applications of their stimuli-responsive properties in different conditions. Poly(N-isopropylacrylamide) (PNIPAM), 1 which exhibits a lower critical solution temperature (LCST)-type transtion, 2 has been considered as one of the most promising thermoresponsive materials because the transition temperature (33°C) is higher than ordinary room temperature and is also quite close to the human body temperature. When the temperature is higher than the LCST, PNIPAM in contact with bulk water undergoes a reversible phase transition from hydrophilic to hydrophobic.14 This phenomena have been widely applied in biological systems, 5,6 as sensors, 7,8 and in smart layers. 912 In the past decades, the mechanism of the LCST-type transition in PNIPAM solutions has been studied by a number of researchers. 1315 The LCST-type transition from a collapse state to a coil state occurs when some hydrated water molecules cluster around the PNIPAM monomer via hydrogen bonding (H 2 O£H 2 O, CO£H 2 O, and NH£H 2 O) at temperatures lower than the LCST. Then when the temperature becomes higher than the LCST, the PNIPAM chain is expelled by hydrophobic interactions with the breaking of these hydrogen bonds. This allows the LCST-type transition from the coil state to the collapse state.However, in many applications, the PNIPAM system is not in direct contact with bulk water, in which case, the thermoresponsive behavior becomes more complicated. 1619 While there have been a number of reports on PNIPAM solutions and brushes, there are limited results for solid ultrathin film cases, particularly in ordinary (moderately wet) atmospheric conditions. Unlike in solution, the solid ultrathin film does not interact with water molecules in a uniform way. As only the surface of the film is exposed to the air, except in the case of direct contact with a water droplet, thermoresponsive behavior has not been expected so far, particularly in the case of ordinary atmospheric conditions. The present paper reports experimentally obtained thermoresponsive behaviors of a PNIPAM solid ultrathin film under ordinary atmospheric conditions. Such observations have been enabled by the real-time X-ray reflectivity technique, 2...

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X-Ray Scattering from Soft-Matter Thin Films

Cited by 478 publications

References 0 publications

X-ray study of the electric double layer at the n-hexane/nanocolloidal silica interface

X-ray study of the electric double layer at the n-hexane/nanocolloidal silica interface

Glass Transition of Ultrathin Sugar Films Probed by X-Ray Reflectivity

Thermoresponsive Behavior of Poly(N-isopropylacrylamide) Solid Ultrathin Film under Ordinary Atmospheric Conditions

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